The present invention relates to a new and improved engine and more specifically to an internal combustion engine in which a relatively lean air-fuel mixture in a main combustion chamber is ignited by initially igniting a relatively rich air-fuel mixture in an auxiliary combustion chamber.
A known internal combustion engine includes a main combustion chamber into which a relatively lean air-fuel mixture is introduced through a first conduit and valve. A relatively rich air-fuel mixture is introduced into an auxiliary combustion chamber through a second conduit and valve. The rich air-fuel mixture in the auxiliary combustion chamber is ignited by a spark plug. The resulting flame is directed into the main combustion chamber to effect ignition of the lean air-fuel mixture therein. An engine having this construction requires two air-fuel conduits and flow control valves for the different air-fuel mixtures.
Another known engine is disclosed in U.S. Pat. No. 2,093,339 and injects fuel only into an auxiliary chamber. During a compression stroke, a spark plug in the auxiliary chamber is energized with a voltage which is insufficient to cause sparking.
Still another known engine is disclosed in U.S. Pat. No. 3,776,212. The engine disclosed in this patent includes a main combustion chamber from which an air-fuel mixture is forced through a nozzle into an auxiliary combustion chamber during a compression stroke of the engine. The fuel in the auxiliary combustion chamber is ignited by a spark plug and the flame is directed into the main combustion chamber to ignite the air-fuel mixture therein. Since the air-fuel mixture in this known engine is forced from the main combustion chamber into the auxiliary combustion chamber, the gases in the auxiliary combustion chamber will have the same air-to-fuel ratio as the gases in the main combustion chamber.
In an effort to improve engine operating efficiency and to enable lean air-fuel mixtures to be utilized, it has been suggested that an electrostatic field by utilized to accumulate fuel droplets adjacent to a spark plug in the manner disclosed in U.S. Pat. No. 3,318,293. Various other arrangements for establishing electrostatic fields are disclosed in Australian Pat. No. 207,196 and U.S. Pat. No. 2,227,714.